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Pogue BW, Zhu TC, Ntziachristos V, Wilson BC, Paulsen KD, Gioux S, Nordstrom R, Pfefer TJ, Tromberg BJ, Wabnitz H, Yodh A, Chen Y, Litorja M. AAPM Task Group Report 311: Guidance for performance evaluation of fluorescence-guided surgery systems. Med Phys 2024; 51:740-771. [PMID: 38054538 DOI: 10.1002/mp.16849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 11/02/2023] [Accepted: 11/06/2023] [Indexed: 12/07/2023] Open
Abstract
The last decade has seen a large growth in fluorescence-guided surgery (FGS) imaging and interventions. With the increasing number of clinical specialties implementing FGS, the range of systems with radically different physical designs, image processing approaches, and performance requirements is expanding. This variety of systems makes it nearly impossible to specify uniform performance goals, yet at the same time, utilization of different devices in new clinical procedures and trials indicates some need for common knowledge bases and a quality assessment paradigm to ensure that effective translation and use occurs. It is feasible to identify key fundamental image quality characteristics and corresponding objective test methods that should be determined such that there are consistent conventions across a variety of FGS devices. This report outlines test methods, tissue simulating phantoms and suggested guidelines, as well as personnel needs and professional knowledge bases that can be established. This report frames the issues with guidance and feedback from related societies and agencies having vested interest in the outcome, coming from an independent scientific group formed from academics and international federal agencies for the establishment of these professional guidelines.
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Affiliation(s)
- Brian W Pogue
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Timothy C Zhu
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Vasilis Ntziachristos
- Institute for Biological and Medical Imaging, Technical University of Munich, Helmholtz Zentrum Munich, Munich, Germany
| | - Brian C Wilson
- Department of Medical Biophysics, University of Toronto, University Health Network, Toronto, Ontario, Canada
| | - Keith D Paulsen
- Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire, USA
| | - Sylvain Gioux
- Department of Biomedical Engineering, University of Strasbourg, Strasbourg, France
| | - Robert Nordstrom
- Cancer Imaging Program, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - T Joshua Pfefer
- Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Bruce J Tromberg
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Arjun Yodh
- Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yu Chen
- Department of Biomedical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Maritoni Litorja
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
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Sudakou A, Wabnitz H, Liemert A, Wolf M, Liebert A. Two-layered blood-lipid phantom and method to determine absorption and oxygenation employing changes in moments of DTOFs. BIOMEDICAL OPTICS EXPRESS 2023; 14:3506-3531. [PMID: 37497481 PMCID: PMC10368065 DOI: 10.1364/boe.492168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/29/2023] [Accepted: 05/29/2023] [Indexed: 07/28/2023]
Abstract
Near-infrared spectroscopy (NIRS) is an established technique for measuring tissue oxygen saturation (StO2), which is of high clinical value. For tissues that have layered structures, it is challenging but clinically relevant to obtain StO2 of the different layers, e.g. brain and scalp. For this aim, we present a new method of data analysis for time-domain NIRS (TD-NIRS) and a new two-layered blood-lipid phantom. The new analysis method enables accurate determination of even large changes of the absorption coefficient (Δµa) in multiple layers. By adding Δµa to the baseline µa, this method provides absolute µa and hence StO2 in multiple layers. The method utilizes (i) changes in statistical moments of the distributions of times of flight of photons (DTOFs), (ii) an analytical solution of the diffusion equation for an N-layered medium, (iii) and the Levenberg-Marquardt algorithm (LMA) to determine Δµa in multiple layers from the changes in moments. The method is suitable for NIRS tissue oximetry (relying on µa) as well as functional NIRS (fNIRS) applications (relying on Δµa). Experiments were conducted on a new phantom, which enabled us to simulate dynamic StO2 changes in two layers for the first time. Two separate compartments, which mimic superficial and deep layers, hold blood-lipid mixtures that can be deoxygenated (using yeast) and oxygenated (by bubbling oxygen) independently. Simultaneous NIRS measurements can be performed on the two-layered medium (variable superficial layer thickness, L), the deep (homogeneous), and/or the superficial (homogeneous). In two experiments involving ink, we increased the nominal µa in one of two compartments from 0.05 to 0.25 cm-1, L set to 14.5 mm. In three experiments involving blood (L set to 12, 15, or 17 mm), we used a protocol consisting of six deoxygenation cycles. A state-of-the-art multi-wavelength TD-NIRS system measured simultaneously on the two-layered medium, as well as on the deep compartment for a reference. The new method accurately determined µa (and hence StO2) in both compartments. The method is a significant progress in overcoming the contamination from the superficial layer, which is beneficial for NIRS and fNIRS applications, and may improve the determination of StO2 in the brain from measurements on the head. The advanced phantom may assist in the ongoing effort towards more realistic standardized performance tests in NIRS tissue oximetry. Data and MATLAB codes used in this study were made publicly available.
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Affiliation(s)
- Aleh Sudakou
- Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
| | - Heidrun Wabnitz
- Physikalisch-Technische Bundesanstalt (PTB), Berlin, Germany
| | - André Liemert
- Institut für Lasertechnologien in der Medizin und Meßtechnik an der Universität Ulm, Germany
| | - Martin Wolf
- Department of Neonatology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Adam Liebert
- Nałęcz Institute of Biocybernetics and Biomedical Engineering Polish Academy of Sciences, Warsaw, Poland
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Chen H, Liu K, Jiang Y, Liu Y, Deng Y. Real-time and accurate estimation ex vivo of four basic optical properties from thin tissue based on a cascade forward neural network. BIOMEDICAL OPTICS EXPRESS 2023; 14:1818-1832. [PMID: 37078046 PMCID: PMC10110315 DOI: 10.1364/boe.489079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 03/22/2023] [Indexed: 05/03/2023]
Abstract
Double integrating sphere measurements obtained from thin ex vivo tissues provides more spectral information and hence allows full estimation of all basic optical properties (OPs) theoretically. However, the ill-conditioned nature of the OP determination increases excessively with the reduction in tissue thickness. Therefore, it is crucial to develop a model for thin ex vivo tissues that is robust to noise. Herein, we present a deep learning solution to precisely extract four basic OPs in real-time from thin ex vivo tissues, leveraging a dedicated cascade forward neural network (CFNN) for each OP with an additional introduced input of the refractive index of the cuvette holder. The results show that the CFNN-based model enables accurate and fast evaluation of OPs, as well as robustness to noise. Our proposed method overcomes the highly ill-conditioned restriction of OP evaluation and can distinguish the effects of slight changes in measurable quantities without any a priori knowledge.
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Affiliation(s)
- Haitao Chen
- School of Engineering Sciences, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Kaixian Liu
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yuxuan Jiang
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yafeng Liu
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yong Deng
- Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
- MoE Key Laboratory for Biomedical Photonics, Department of Biomedical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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Efficient computation of the steady-state and time-domain solutions of the photon diffusion equation in layered turbid media. Sci Rep 2022; 12:18979. [PMID: 36347893 PMCID: PMC9643457 DOI: 10.1038/s41598-022-22649-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 10/18/2022] [Indexed: 11/09/2022] Open
Abstract
Accurate and efficient forward models of photon migration in heterogeneous geometries are important for many applications of light in medicine because many biological tissues exhibit a layered structure of independent optical properties and thickness. However, closed form analytical solutions are not readily available for layered tissue-models, and often are modeled using computationally expensive numerical techniques or theoretical approximations that limit accuracy and real-time analysis. Here, we develop an open-source accurate, efficient, and stable numerical routine to solve the diffusion equation in the steady-state and time-domain for a layered cylinder tissue model with an arbitrary number of layers and specified thickness and optical coefficients. We show that the steady-state ([Formula: see text] ms) and time-domain ([Formula: see text] ms) fluence (for an 8-layer medium) can be calculated with absolute numerical errors approaching machine precision. The numerical implementation increased computation speed by 3 to 4 orders of magnitude compared to previously reported theoretical solutions in layered media. We verify our solutions asymptotically to homogeneous tissue geometries using closed form analytical solutions to assess convergence and numerical accuracy. Approximate solutions to compute the reflected intensity are presented which can decrease the computation time by an additional 2-3 orders of magnitude. We also compare our solutions for 2, 3, and 5 layered media to gold-standard Monte Carlo simulations in layered tissue models of high interest in biomedical optics (e.g. skin/fat/muscle and brain). The presented routine could enable more robust real-time data analysis tools in heterogeneous tissues that are important in many clinical applications such as functional brain imaging and diffuse optical spectroscopy.
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Rudraiah PS, Duadi H, Fixler D. Bottom layer absorption coefficients extraction from two-layer phantoms based on crossover point in diffuse reflectance. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210253R. [PMID: 34850612 PMCID: PMC8630471 DOI: 10.1117/1.jbo.26.11.117001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
SIGNIFICANCE Numerous optical imaging and spectroscopy techniques are used to study the tissue-optical properties; the majority of them are limited in information regarding the penetration depth. A simple, safe, easily applicable diagnostic technique is required to get deeper tissue information in a multilayer structure. AIM A fiber-based diffuse reflectance (DR) technique is used to extract and quantify the bottom layer absorption coefficients in two-layer (2L) tissue-mimicking solid phantoms. We determine the Indian black ink concentrations in a deep-hidden layer that is sandwiched between agar and silicone-based phantom layers. APPROACH A fiber-based DR experiment was performed to study the optical properties of the tissue at higher penetration depth, with different fiber core diameters and a constant numerical aperture (0.5 NA). The optimal core diameter of the fiber was chosen by measuring solid phantoms. In 2L phantoms, the thickness of the top layer was kept 5.5 mm with a constant absorption and reduced scattering coefficients (μa = 0.045 mm - 1 and μs ' = 2.622 mm - 1), whereas the absorption coefficients of the bottom layers were varied from 0.014 to 0.037 mm - 1 keeping the μs ' the same as the top layer. A unique crossover point (Cp) was found in the DR intensity profile against distance. We examined the slope before and after the Cp. These two slopes indicate the difference between the optical properties of the top and bottom layers. Our technique got further verification, as we successfully determined the Cp with different Indian black ink concentrations, placed at the junction between the agar and silicone-based phantom layers. RESULTS The DR measurements were applied to 2L phantoms. Two different slopes were found in 2L phantoms compared to the one-layer (optical properties equal to the top layer of 2L). We extracted the slopes before and after the Cp in the 2L phantoms. The calculated absorption coefficients before the Cp were 0.014 ± 0.0004, 0.022 ± 0.0003, 0.028 ± 0.0003, and 0.036 ± 0.0014 mm - 1, and the absorption coefficients after the Cp were 0.019 ± 0.0013, 0.013 ± 0.0004, 0.014 ± 0.0006, and 0.031 ± 0.0001 mm - 1, respectively. The calculated absorption coefficients before the Cp were in good agreement with the optical properties of the bottom layer. The calculated absorption coefficients after the Cp were not the same as the top layer. Our DR system successfully determines the crossover points 12.14 ± 0.11 and 11.73 ± 0.15 mm for 70% and 100% ink concentrations placed at the junction of the agar and silicone layers. CONCLUSIONS In a 2L tissue structure, the Cp depends on the absorption coefficients of top and bottom layers and the thickness of the top layer. With the help of the Cp and the absorption coefficients, one can determine the thickness of the top layer or vice versa. The slope value before the Cp in the DR profile allowed us to determine the absorption properties of the bottom layer instead of having the average behavior of the 2L phantom in the far detection range (11.0 to 17.0 mm).
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Affiliation(s)
- Pavitra S. Rudraiah
- Bar Ilan University, Faculty of Engineering and Institute of Nanotechnology and Advanced Materials, Ramat Gan, Israel
| | - Hamootal Duadi
- Bar Ilan University, Faculty of Engineering and Institute of Nanotechnology and Advanced Materials, Ramat Gan, Israel
| | - Dror Fixler
- Bar Ilan University, Faculty of Engineering and Institute of Nanotechnology and Advanced Materials, Ramat Gan, Israel
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Stier AC, Goth W, Hurley A, Brown T, Feng X, Zhang Y, Lopes FCPS, Sebastian KR, Ren P, Fox MC, Reichenberg JS, Markey MK, Tunnell JW. Imaging sub-diffuse optical properties of cancerous and normal skin tissue using machine learning-aided spatial frequency domain imaging. JOURNAL OF BIOMEDICAL OPTICS 2021; 26:JBO-210048RR. [PMID: 34558235 PMCID: PMC8459901 DOI: 10.1117/1.jbo.26.9.096007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 08/27/2021] [Indexed: 05/28/2023]
Abstract
SIGNIFICANCE Sub-diffuse optical properties may serve as useful cancer biomarkers, and wide-field heatmaps of these properties could aid physicians in identifying cancerous tissue. Sub-diffuse spatial frequency domain imaging (sd-SFDI) can reveal such wide-field maps, but the current time cost of experimentally validated methods for rendering these heatmaps precludes this technology from potential real-time applications. AIM Our study renders heatmaps of sub-diffuse optical properties from experimental sd-SFDI images in real time and reports these properties for cancerous and normal skin tissue subtypes. APPROACH A phase function sampling method was used to simulate sd-SFDI spectra over a wide range of optical properties. A machine learning model trained on these simulations and tested on tissue phantoms was used to render sub-diffuse optical property heatmaps from sd-SFDI images of cancerous and normal skin tissue. RESULTS The model accurately rendered heatmaps from experimental sd-SFDI images in real time. In addition, heatmaps of a small number of tissue samples are presented to inform hypotheses on sub-diffuse optical property differences across skin tissue subtypes. CONCLUSION These results bring the overall process of sd-SFDI a fundamental step closer to real-time speeds and set a foundation for future real-time medical applications of sd-SFDI such as image guided surgery.
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Affiliation(s)
- Andrew C. Stier
- The University of Texas at Austin, Department of Electrical and Computer Engineering, Austin, Texas, United States
| | - Will Goth
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Aislinn Hurley
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Treshayla Brown
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Xu Feng
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Yao Zhang
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Fabiana C. P. S. Lopes
- The University of Texas at Austin, Dell Medical School, Department of Internal Medicine, Austin, Texas, United States
| | - Katherine R. Sebastian
- The University of Texas at Austin, Dell Medical School, Department of Internal Medicine, Austin, Texas, United States
| | - Pengyu Ren
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Matthew C. Fox
- The University of Texas at Austin, Dell Medical School, Department of Internal Medicine, Austin, Texas, United States
| | - Jason S. Reichenberg
- The University of Texas at Austin, Dell Medical School, Department of Internal Medicine, Austin, Texas, United States
| | - Mia K. Markey
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
- The University of Texas MD Anderson Cancer Center, Imaging Physics Residency Program, Houston, Texas, United States
| | - James W. Tunnell
- The University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
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Post AL, de Groof AJ, Zhang XU, Swager AF, Fockens KN, Pouw RE, Weusten BLAM, Faber DJ, de Bruin DM, Bergman JJGHM, van Leeuwen TG, Sterenborg HJCM, Curvers WL. Toward improved endoscopic surveillance with multidiameter single fiber reflectance spectroscopy in patients with Barrett's esophagus. JOURNAL OF BIOPHOTONICS 2021; 14:e202000351. [PMID: 33410602 DOI: 10.1002/jbio.202000351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 05/05/2023]
Abstract
Patients with Barrett's esophagus are at an increased risk to develop esophageal cancer and, therefore, undergo regular endoscopic surveillance. Early detection of neoplasia enables endoscopic treatment, which improves outcomes. However, early Barrett's neoplasia is easily missed during endoscopic surveillance. This study investigates multidiameter single fiber reflectance spectroscopy (MDSFR) to improve Barrett's surveillance. Based on the concept of field cancerization, it may be possible to identify the presence of a neoplastic lesion from measurements elsewhere in the esophagus or even the oral cavity. In this study, MDSFR measurements are performed on non-dysplastic Barrett's mucosa, squamous mucosa, oral mucosa, and the neoplastic lesion (if present). Based on logistic regression analysis on the scattering parameters measured by MDSFR, a classifier is developed that can predict the presence of neoplasia elsewhere in the Barrett's segment from measurements on the non-dysplastic Barrett's mucosa (sensitivity 91%, specificity 71%, AUC = 0.77). Classifiers obtained from logistic regression analysis for the squamous and oral mucosa do not result in an AUC significantly different from 0.5.
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Affiliation(s)
- Anouk L Post
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Department of Surgery, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Albert J de Groof
- Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Xu U Zhang
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Anne-Fré Swager
- Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Kiki N Fockens
- Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Roos E Pouw
- Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Bas L A M Weusten
- Department of Gastroenterology and Hepatology, St. Antonius Hospital, Nieuwegein, The Netherlands
- Department of Gastroenterology and Hepatology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Dirk J Faber
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Daniel M de Bruin
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Jacques J G H M Bergman
- Department of Gastroenterology and Hepatology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Ton G van Leeuwen
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Henricus J C M Sterenborg
- Department of Biomedical Engineering and Physics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
- Department of Surgery, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Wouter L Curvers
- Department of Gastroenterology and Hepatology, Catharina Hospital, Eindhoven, The Netherlands
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Bahrani AA, Kong W, Shang Y, Huang C, Smith CD, Powell DK, Jiang Y, Rayapati AO, Jicha GA, Yu G. Diffuse optical assessment of cerebral-autoregulation in older adults stratified by cerebrovascular risk. JOURNAL OF BIOPHOTONICS 2020; 13:e202000073. [PMID: 32533642 PMCID: PMC8824485 DOI: 10.1002/jbio.202000073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/06/2020] [Accepted: 06/09/2020] [Indexed: 05/04/2023]
Abstract
Diagnosis of cerebrovascular disease (CVD) at early stages is essential for preventing sequential complications. CVD is often associated with abnormal cerebral microvasculature, which may impact cerebral-autoregulation (CA). A novel hybrid near-infrared diffuse optical instrument and a finger plethysmograph were used to simultaneously detect low-frequency oscillations (LFOs) of cerebral blood flow (CBF), oxy-hemoglobin concentration ([HbO2 ]), deoxy-hemoglobin concentration ([Hb]) and mean arterial pressure (MAP) in older adults before, during and after 70° head-up-tilting (HUT). The participants with valid data were divided based on Framingham risk score (FRS, 1-30 points) into low-risk (FRS ≤15, n = 13) and high-risk (FRS >15, n = 11) groups for developing CVD. The LFO gains were determined by transfer function analyses with MAP as the input, and CBF, [HbO2 ] and [Hb] as the outputs (CA ∝ 1/Gain). At resting-baseline, LFO gains in the high-risk group were relatively lower compared to the low-risk group. The lower baseline gains in the high-risk group may attribute to compensatory mechanisms to maintain stronger steady-state CAs. However, HUT resulted in smaller gain reductions in the high-risk group compared to the low-risk group, suggesting weaker dynamic CAs. LFO gains are potentially valuable biomarkers for early detection of CVD based on associations with CAs.
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Affiliation(s)
- Ahmed A. Bahrani
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Biomedical Engineering Department, Al-Khwarizmi College of Engineering, University of Baghdad, Baghdad, Iraq
| | - Weikai Kong
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
| | - Yu Shang
- Shanxi Provincial Key Laboratory for Biomedical Imaging and Big Data, North University of China, Shanxi, China
| | - Chong Huang
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
| | - Charles D. Smith
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Department of Neurology, University of Kentucky, Lexington, Kentucky
| | - David K. Powell
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Neuroscience Department, University of Kentucky, Lexington, Kentucky
| | - Yang Jiang
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Department of Behavioral Science, University of Kentucky, Lexington, Kentucky
| | - Abner O. Rayapati
- Department of Psychiatry, University of Kentucky, Lexington, Kentucky
| | - Gregory A. Jicha
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky
- Magnetic Resonance Imaging and Spectroscopy Center (MRISC), University of Kentucky, Lexington, Kentucky
- Department of Neurology, University of Kentucky, Lexington, Kentucky
| | - Guoqiang Yu
- Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky
- Correspondence: Guoqiang Yu, Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506,
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Andrus L, Mau T, Ben-Yakar A. Scattering properties and femtosecond laser ablation thresholds of human and canine vocal folds at 776-nm wavelength. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-7. [PMID: 31468749 PMCID: PMC6983523 DOI: 10.1117/1.jbo.24.8.085005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 08/14/2019] [Indexed: 06/10/2023]
Abstract
Ultrafast laser ablation may provide a treatment for vocal fold (VF) scarring. Optical properties of VFs must be known prior to clinical implementation to select appropriate laser surgery conditions. We present scattering lengths of epithelium ℓs , ep, superficial lamina propria ℓs , SLP, and ablation thresholds Fth of human and canine VF tissues. Our experimental approach involves an image-guided, laser-ablation-based method that allows for simultaneous determination of ℓs and Fth in these multilayered tissues. Studying eight canine samples, we found ℓs , ep = 75.3 ± 5.7 μm, ℓs , SLP = 26.1 ± 1.2 μm, Fth , ep = 1.58 ± 0.06 J / cm2, and Fth , SLP = 1.55 ± 0.17 J / cm2. Studying five human samples, we found ℓs , ep = 42.8 ± 3.3 μm and Fth , ep = 1.66 ± 0.10 J / cm2. We studied the effects of cumulative pulse overlap on ablation threshold and found no significant variations beyond 12 overlapping pulses. Interestingly, our studies about the effect of sample storage on the scattering properties of porcine VF show a 60% increase in ℓs , ep for fresh porcine VF when compared to the same sample stored in isotonic solution. These results provide guidelines for clinical implementation by enabling selection of optimal laser surgery parameters for subsurface ablation of VF tissues.
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Affiliation(s)
- Liam Andrus
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Ted Mau
- University of Texas Southwestern Medical Center, Department of Otolaryngology-Head and Neck Surgery, Dallas, Texas, United States
| | - Adela Ben-Yakar
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
- University of Texas at Austin, Department of Mechanical Engineering, Austin, Texas, United States
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10
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Hsieh HP, Ko FH, Sung KB. Hybrid method to estimate two-layered superficial tissue optical properties from simulated data of diffuse reflectance spectroscopy. APPLIED OPTICS 2018; 57:3038-3046. [PMID: 29714335 DOI: 10.1364/ao.57.003038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/12/2018] [Indexed: 06/08/2023]
Abstract
An iterative curve fitting method has been applied in both simulation [J. Biomed. Opt.17, 107003 (2012)JBOPFO1083-366810.1117/1.JBO.17.10.107003] and phantom [J. Biomed. Opt.19, 077002 (2014)JBOPFO1083-366810.1117/1.JBO.19.7.077002] studies to accurately extract optical properties and the top layer thickness of a two-layered superficial tissue model from diffuse reflectance spectroscopy (DRS) data. This paper describes a hybrid two-step parameter estimation procedure to address two main issues of the previous method, including (1) high computational intensity and (2) converging to local minima. The parameter estimation procedure contained a novel initial estimation step to obtain an initial guess, which was used by a subsequent iterative fitting step to optimize the parameter estimation. A lookup table was used in both steps to quickly obtain reflectance spectra and reduce computational intensity. On simulated DRS data, the proposed parameter estimation procedure achieved high estimation accuracy and a 95% reduction of computational time compared to previous studies. Furthermore, the proposed initial estimation step led to better convergence of the following fitting step. Strategies used in the proposed procedure could benefit both the modeling and experimental data processing of not only DRS but also related approaches such as near-infrared spectroscopy.
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Glennie DL, Hayward JE, Farrell TJ. Modeling changes in the hemoglobin concentration of skin with total diffuse reflectance spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:035002. [PMID: 25751028 DOI: 10.1117/1.jbo.20.3.035002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 02/16/2015] [Indexed: 05/20/2023]
Abstract
The ability to monitor changes in the concentration of hemoglobin in the blood of the skin in real time is a key component to personalized patient care. Since hemoglobin has a unique absorption spectrum in the visible light range, diffuse reflectance spectroscopy is the most common approach. Although the collection of the diffuse reflectance spectrum with an integrating sphere (IS) has several calibration challenges, this collection method is sufficiently user-friendly that it may be worth overcoming the initial difficulty. Once the spectrum is obtained, it is commonly interpreted with a log-inverse-reflectance (LIR) or “absorbance” analysis that can only accurately monitor changes in the hemoglobin concentration when there are no changes to the nonhemoglobin chromophore concentrations which is not always the case. We address the difficulties associated with collection of the diffuse reflectance spectrum with an IS and propose a model capable of retrieving relative changes in hemoglobin concentration from the visible light spectrum. The model is capable of accounting for concentration changes in the nonhemoglobin chromophores and is first characterized with theoretical spectra and liquid phantoms. The model is then used in comparison with a common LIR analysis on temporal measurements from blanched and reddened human skin.
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Affiliation(s)
- Diana L Glennie
- McMaster University, Department of Medical Physics and Applied Radiation Sciences, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada
| | - Joseph E Hayward
- McMaster University, Department of Medical Physics and Applied Radiation Sciences, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, CanadabJuravinski Cancer Centre, Department of Medical Physics, 699 Concession Street, Hamilton, Ontario, L8V 5C2, Canada
| | - Thomas J Farrell
- McMaster University, Department of Medical Physics and Applied Radiation Sciences, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, CanadabJuravinski Cancer Centre, Department of Medical Physics, 699 Concession Street, Hamilton, Ontario, L8V 5C2, Canada
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12
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Baker WB, Parthasarathy AB, Busch DR, Mesquita RC, Greenberg JH, Yodh AG. Modified Beer-Lambert law for blood flow. BIOMEDICAL OPTICS EXPRESS 2014; 5:4053-75. [PMID: 25426330 PMCID: PMC4242038 DOI: 10.1364/boe.5.004053] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 10/14/2014] [Accepted: 10/15/2014] [Indexed: 05/18/2023]
Abstract
We develop and validate a Modified Beer-Lambert law for blood flow based on diffuse correlation spectroscopy (DCS) measurements. The new formulation enables blood flow monitoring from temporal intensity autocorrelation function data taken at single or multiple delay-times. Consequentially, the speed of the optical blood flow measurement can be substantially increased. The scheme facilitates blood flow monitoring of highly scattering tissues in geometries wherein light propagation is diffusive or non-diffusive, and it is particularly well-suited for utilization with pressure measurement paradigms that employ differential flow signals to reduce contributions of superficial tissues.
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Affiliation(s)
- Wesley B. Baker
- Dept. Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104,
USA
| | | | - David R. Busch
- Dept. Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104,
USA
- Div. of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104,
USA
| | - Rickson C. Mesquita
- Institute of Physics, University of Campinas, Campinas, SP 13083-859,
Brazil
| | - Joel H. Greenberg
- Dept. Neurology, University of Pennsylvania, Philadelphia, PA 19104,
USA
| | - A. G. Yodh
- Dept. Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104,
USA
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13
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Steinberg I, Harbater O, Gannot I. Robust estimation of cerebral hemodynamics in neonates using multilayered diffusion model for normal and oblique incidences. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:71406. [PMID: 24604607 DOI: 10.1117/1.jbo.19.7.071406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 01/27/2014] [Indexed: 06/03/2023]
Abstract
The diffusion approximation is useful for many optical diagnostics modalities, such as near-infrared spectroscopy. However, the simple normal incidence, semi-infinite layer model may prove lacking in estimation of deep-tissue optical properties such as required for monitoring cerebral hemodynamics, especially in neonates. To answer this need, we present an analytical multilayered, oblique incidence diffusion model. Initially, the model equations are derived in vector-matrix form to facilitate fast and simple computation. Then, the spatiotemporal reflectance predicted by the model for a complex neonate head is compared with time-resolved Monte Carlo (TRMC) simulations under a wide range of physiologically feasible parameters. The high accuracy of the multilayer model is demonstrated in that the deviation from TRMC simulations is only a few percent even under the toughest conditions. We then turn to solve the inverse problem and estimate the oxygen saturation of deep brain tissues based on the temporal and spatial behaviors of the reflectance. Results indicate that temporal features of the reflectance are more sensitive to deep-layer optical parameters. The accuracy of estimation is shown to be more accurate and robust than the commonly used single-layer diffusion model. Finally, the limitations of such approaches are discussed thoroughly.
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14
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Liao YK, Tseng SH. Reliable recovery of the optical properties of multi-layer turbid media by iteratively using a layered diffusion model at multiple source-detector separations. BIOMEDICAL OPTICS EXPRESS 2014; 5:975-89. [PMID: 24688828 PMCID: PMC3959844 DOI: 10.1364/boe.5.000975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 02/09/2014] [Accepted: 02/21/2014] [Indexed: 05/13/2023]
Abstract
Accurately determining the optical properties of multi-layer turbid media using a layered diffusion model is often a difficult task and could be an ill-posed problem. In this study, an iterative algorithm was proposed for solving such problems. This algorithm employed a layered diffusion model to calculate the optical properties of a layered sample at several source-detector separations (SDSs). The optical properties determined at various SDSs were mutually referenced to complete one round of iteration and the optical properties were gradually revised in further iterations until a set of stable optical properties was obtained. We evaluated the performance of the proposed method using frequency domain Monte Carlo simulations and found that the method could robustly recover the layered sample properties with various layer thickness and optical property settings. It is expected that this algorithm can work with photon transport models in frequency and time domain for various applications, such as determination of subcutaneous fat or muscle optical properties and monitoring the hemodynamics of muscle.
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Affiliation(s)
- Yu-Kai Liao
- Department of Photonics, National Cheng-Kung University, Tainan 701, Taiwan
| | - Sheng-Hao Tseng
- Department of Photonics, National Cheng-Kung University, Tainan 701, Taiwan
- Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701, Taiwan
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15
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Cheng R, Shang Y, Wang S, Evans JM, Rayapati A, Randall DC, Yu G. Near-infrared diffuse optical monitoring of cerebral blood flow and oxygenation for the prediction of vasovagal syncope. JOURNAL OF BIOMEDICAL OPTICS 2014; 19:17001. [PMID: 24402372 PMCID: PMC3884846 DOI: 10.1117/1.jbo.19.1.017001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 12/01/2013] [Accepted: 12/10/2013] [Indexed: 05/21/2023]
Abstract
Significant drops in arterial blood pressure and cerebral hemodynamics have been previously observed during vasovagal syncope (VVS). Continuous and simultaneous monitoring of these physiological variables during VVS is rare, but critical for determining which variable is the most sensitive parameter to predict VVS. The present study used a novel custom-designed diffuse correlation spectroscopy flow-oximeter and a finger plethysmograph to simultaneously monitor relative changes of cerebral blood flow (rCBF), cerebral oxygenation (i.e., oxygenated/deoxygenated/total hemoglobin concentration: r[HbO2]/r[Hb]/rTHC), and mean arterial pressure (rMAP) during 70 deg head-up tilt (HUT) in 14 healthy adults. Six subjects developed presyncope during HUT. Two-stage physiological responses during HUT were observed in the presyncopal group: slow and small changes in measured variables (i.e., Stage I), followed by rapid and dramatic decreases in rMAP, rCBF, r[HbO2], and rTHC (i.e., Stage II). Compared to other physiological variables, rCBF reached its breakpoint between the two stages earliest and had the largest decrease (76±8%) during presyncope. Our results suggest that rCBF has the best sensitivity for the assessment of VVS. Most importantly, a threshold of ∼50% rCBF decline completely separated the subjects from those without presyncope, suggesting its potential for predicting VVS.
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Affiliation(s)
- Ran Cheng
- University of Kentucky, Department of Biomedical Engineering, Lexington, Kentucky 40506
| | - Yu Shang
- University of Kentucky, Department of Biomedical Engineering, Lexington, Kentucky 40506
| | - Siqi Wang
- University of Kentucky, Department of Biomedical Engineering, Lexington, Kentucky 40506
| | - Joyce M. Evans
- University of Kentucky, Department of Biomedical Engineering, Lexington, Kentucky 40506
| | - Abner Rayapati
- University of Kentucky, Department of Psychiatry, Lexington, Kentucky 40509
| | - David C. Randall
- University of Kentucky, Department of Biomedical Engineering, Lexington, Kentucky 40506
- University of Kentucky, Department of Physiology, Lexington, Kentucky 40536
| | - Guoqiang Yu
- University of Kentucky, Department of Biomedical Engineering, Lexington, Kentucky 40506
- Address all correspondence to: Guoqiang Yu, E-mail:
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16
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Sharma M, Hennessy R, Markey MK, Tunnell JW. Verification of a two-layer inverse Monte Carlo absorption model using multiple source-detector separation diffuse reflectance spectroscopy. BIOMEDICAL OPTICS EXPRESS 2013; 5:40-53. [PMID: 24466475 PMCID: PMC3891344 DOI: 10.1364/boe.5.000040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 11/15/2013] [Accepted: 11/21/2013] [Indexed: 05/11/2023]
Abstract
A two-layer Monte Carlo lookup table-based inverse model is validated with two-layered phantoms across physiologically relevant optical property ranges. Reflectance data for source-detector separations of 370 μm and 740 μm were collected from these two-layered phantoms and top layer thickness, reduced scattering coefficient and the top and bottom layer absorption coefficients were extracted using the inverse model and compared to the known values. The results of the phantom verification show that this method is able to accurately extract top layer thickness and scattering when the top layer thickness ranges from 0 to 550 μm. In this range, top layer thicknesses were measured with an average error of 10% and the reduced scattering coefficient was measured with an average error of 15%. The accuracy of top and bottom layer absorption coefficient measurements was found to be highly dependent on top layer thickness, which agrees with physical expectation; however, within appropriate thickness ranges, the error for absorption properties varies from 12-25%.
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Affiliation(s)
- Manu Sharma
- Biomedical Engineering, The University of Texas at Austin 107 W. Dean Keeton, Austin, TX, 78712
USA
- These authors contributed equally to this paper
| | - Ricky Hennessy
- Biomedical Engineering, The University of Texas at Austin 107 W. Dean Keeton, Austin, TX, 78712
USA
- These authors contributed equally to this paper
| | - Mia K. Markey
- Biomedical Engineering, The University of Texas at Austin 107 W. Dean Keeton, Austin, TX, 78712
USA
- Imaging Physics, The University of Texas MD Anderson Cancer Center 1515 Holcombe Boulevard, Houston, TX, 77030
USA
| | - James W. Tunnell
- Biomedical Engineering, The University of Texas at Austin 107 W. Dean Keeton, Austin, TX, 78712
USA
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17
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Cheng R, Shang Y, Hayes D, Saha SP, Yu G. Noninvasive optical evaluation of spontaneous low frequency oscillations in cerebral hemodynamics. Neuroimage 2012; 62:1445-54. [DOI: 10.1016/j.neuroimage.2012.05.069] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 05/11/2012] [Accepted: 05/24/2012] [Indexed: 01/15/2023] Open
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18
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Wang Q, Le D, Ramella-Roman J, Pfefer J. Broadband ultraviolet-visible optical property measurement in layered turbid media. BIOMEDICAL OPTICS EXPRESS 2012; 3:1226-40. [PMID: 22741070 PMCID: PMC3370964 DOI: 10.1364/boe.3.001226] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 04/20/2012] [Accepted: 04/23/2012] [Indexed: 05/04/2023]
Abstract
The ability to accurately measure layered biological tissue optical properties (OPs) may improve understanding of spectroscopic device performance and facilitate early cancer detection. Towards these goals, we have performed theoretical and experimental evaluations of an approach for broadband measurement of absorption and reduced scattering coefficients at ultraviolet-visible wavelengths. Our technique is based on neural network (NN) inverse models trained with diffuse reflectance data from condensed Monte Carlo simulations. Experimental measurements were performed from 350 to 600 nm with a fiber-optic-based reflectance spectroscopy system. Two-layer phantoms incorporating OPs relevant to normal and dysplastic mucosal tissue and superficial layer thicknesses of 0.22 and 0.44 mm were used to assess prediction accuracy. Results showed mean OP estimation errors of 19% from the theoretical analysis and 27% from experiments. Two-step NN modeling and nonlinear spectral fitting approaches helped improve prediction accuracy. While limitations and challenges remain, the results of this study indicate that our technique can provide moderately accurate estimates of OPs in layered turbid media.
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Affiliation(s)
- Quanzeng Wang
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Du Le
- Department of Biomedical Engineering, Catholic University of America, Washington, DC 20064, USA
| | - Jessica Ramella-Roman
- Department of Biomedical Engineering, Catholic University of America, Washington, DC 20064, USA
| | - Joshua Pfefer
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, MD 20993, USA
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19
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Sandell JL, Zhu TC. A review of in-vivo optical properties of human tissues and its impact on PDT. JOURNAL OF BIOPHOTONICS 2011; 4:773-87. [PMID: 22167862 PMCID: PMC3321368 DOI: 10.1002/jbio.201100062] [Citation(s) in RCA: 193] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
A thorough understanding of optical properties of biological tissues is critical to effective treatment planning for therapies such as photodynamic therapy (PDT). In the last two decades, new technologies, such as broadband diffuse spectroscopy, have been developed to obtain in vivo data in humans that was not possible before. We found that the in vivo optical properties generally vary in the ranges μ(a) = 0.03-1.6 cm⁻¹ and μ'(s) = 1.2-40 cm⁻¹, although the actual range is tissue-type dependent. We have also examined the overall trend of the absorption spectra (for μ(a) and μ'(s)) as a function of wavelength within a 95% confidence interval for various tissues in vivo. The impact of optical properties on light fluence rate is also discussed for various light application geometries including superficial, interstitial, and within a cavity.
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Affiliation(s)
- Julia L. Sandell
- Department of Radiation Oncology. University of Pennsylvania, Philadelphia, PA 19104
| | - Timothy C. Zhu
- Department of Radiation Oncology. University of Pennsylvania, Philadelphia, PA 19104
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20
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Shang Y, Cheng R, Dong L, Ryan SJ, Saha SP, Yu G. Cerebral monitoring during carotid endarterectomy using near-infrared diffuse optical spectroscopies and electroencephalogram. Phys Med Biol 2011; 56:3015-32. [PMID: 21508444 DOI: 10.1088/0031-9155/56/10/008] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Intraoperative monitoring of cerebral hemodynamics during carotid endarterectomy (CEA) provides essential information for detecting cerebral hypoperfusion induced by temporary internal carotid artery (ICA) clamping and post-CEA hyperperfusion syndrome. This study tests the feasibility and sensitivity of a novel dual-wavelength near-infrared diffuse correlation spectroscopy technique in detecting cerebral blood flow (CBF) and cerebral oxygenation in patients undergoing CEA. Two fiber-optic probes were taped on both sides of the forehead for cerebral hemodynamic measurements, and the instantaneous decreases in CBF and electroencephalogram (EEG) alpha-band power during ICA clamping were compared to test the measurement sensitivities of the two techniques. The ICA clamps resulted in significant CBF decreases (-24.7 ± 7.3%) accompanied with cerebral deoxygenation at the surgical sides (n = 12). The post-CEA CBF were significantly higher (+43.2 ± 16.9%) than the pre-CEA CBF. The CBF responses to ICA clamping were significantly faster, larger and more sensitive than EEG responses. Simultaneous monitoring of CBF, cerebral oxygenation and EEG power provides a comprehensive evaluation of cerebral physiological status, thus showing potential for the adoption of acute interventions (e.g., shunting, medications) during CEA to reduce the risks of severe cerebral ischemia and cerebral hyperperfusion syndrome.
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Affiliation(s)
- Yu Shang
- Center for Biomedical Engineering, University of Kentucky, KY, USA
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21
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Yu G, Shang Y, Zhao Y, Cheng R, Dong L, Saha SP. Intraoperative evaluation of revascularization effect on ischemic muscle hemodynamics using near-infrared diffuse optical spectroscopies. JOURNAL OF BIOMEDICAL OPTICS 2011; 16:027004. [PMID: 21361707 PMCID: PMC3061333 DOI: 10.1117/1.3533320] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Arterial revascularization in patients with peripheral arterial disease (PAD) reestablishes large arterial blood supply to the ischemic muscles in lower extremities via bypass grafts or percutaneous transluminal angioplasty (PTA). Currently no gold standard is available for assessment of revascularization effects in lower extremity muscles. This study tests a novel near-infrared diffuse correlation spectroscopy flow-oximeter for monitoring of blood flow and oxygenation changes in medial gastrocnemius (calf) muscles during arterial revascularization. Twelve limbs with PAD undergoing revascularization were measured using a sterilized fiber-optic probe taped on top of the calf muscle. The optical measurement demonstrated sensitivity to dynamic physiological events, such as arterial clamping/releasing during bypass graft and balloon inflation/deflation during PTA. Significant elevations in calf muscle blood flow were observed after revascularization in patients with bypass graft (+48.1 ± 17.5%) and patients with PTA (+43.2 ± 11.0%), whereas acute post-revascularization effects in muscle oxygenation were not evident. The decoupling of flow and oxygenation after revascularization emphasizes the need for simultaneous measurement of both parameters. The acute elevations/improvements in calf muscle blood flow were associated with significant improvements in symptoms and functions. In total, the investigation corroborates potential of the optical methods for objectively assessing the success of arterial revascularization.
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Affiliation(s)
- Guoqiang Yu
- University of Kentucky, Center for Biomedical Engineering, Lexington, Kentucky 40506-0070, USA.
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22
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Wang Q, Shastri K, Pfefer TJ. Experimental and theoretical evaluation of a fiber-optic approach for optical property measurement in layered epithelial tissue. APPLIED OPTICS 2010; 49:5309-20. [PMID: 20885467 DOI: 10.1364/ao.49.005309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Improvements in measurement of epithelial tissue optical properties (OPs) in the ultraviolet and visible (UV-Vis) may lead to enhanced understanding of optical techniques for neoplasia detection. In this study, we investigated an approach based on fiber-optic measurement of reflectance to determine absorption and reduced scattering coefficients (μ(a) and μ(s)') in two-layer turbid media. Neural network inverse models were trained on simulation data for a wide variety of OP combinations (μ(a) = 1-22.5, μ(s)' = 5-42.5 cm(-1)). Experimental measurements of phantoms with top-layer thicknesses (D) ranging from 0.22 to 0.66 mm were performed at three UV-Vis wavelengths. OP estimation accuracy was calculated and compared to theoretical results. Mean prediction errors were strongly correlated with D and ranged widely, from 1.5 to 12.1 cm(-1). Theoretical analyses indicated the potential for improving accuracy with alternate probe geometries. Although numerous challenges remain, this initial experimental study of an unconstrained approach for fiber-optic-based OP determination in two-layer epithelial tissue indicates the potential to provide useful measurements.
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Affiliation(s)
- Quanzeng Wang
- Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, Maryland 20993, USA.
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23
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Glennie DL, Farrell TJ, Hayward JE, Patterson MS. Integrating spheres for improved skin photodynamic therapy. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:058001. [PMID: 21054127 DOI: 10.1117/1.3484261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The prescribed radiant exposures for photodynamic therapy (PDT) of superficial skin cancers are chosen empirically to maximize the success of the treatment while minimizing adverse reactions for the majority of patients. They do not take into account the wide range of tissue optical properties for human skin, contributing to relatively low treatment success rates. Additionally, treatment times can be unnecessarily long for large treatment areas if the laser power is not sufficient. Both of these concerns can be addressed by the incorporation of an integrating sphere into the irradiation apparatus. The light fluence rate can be increased by as much as 100%, depending on the tissue optical properties. This improvement can be determined in advance of treatment by measuring the reflectance from the tissue through a side port on the integrating sphere, allowing for patient-specific treatment times. The sphere is also effective at improving beam flatness, and reducing the penumbra, creating a more uniform light field. The side port reflectance measurements are also related to the tissue transport albedo, enabling an approximation of the penetration depth, which is useful for real-time light dosimetry.
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Affiliation(s)
- Diana L Glennie
- McMaster University, Department of Medical Physics and Applied Radiation Sciences, 1280 Main Street West, Hamilton, Ontario, Canada.
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24
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Shang Y, Symons TB, Durduran T, Yodh AG, Yu G. Effects of muscle fiber motion on diffuse correlation spectroscopy blood flow measurements during exercise. BIOMEDICAL OPTICS EXPRESS 2010; 1:500-511. [PMID: 21258485 PMCID: PMC3018004 DOI: 10.1364/boe.1.000500] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 08/01/2010] [Accepted: 08/01/2010] [Indexed: 05/03/2023]
Abstract
The influence of muscle fiber motion during exercise on diffuse correlation spectroscopy (DCS) measurements of skeletal muscle blood flow is explored. Isotonic (with muscle fiber motion) and isometric (without muscle fiber motion) plantar flexion exercises were performed at 30% of maximal force on a dynamometer, and muscle blood flow was continuously monitored on the medial gastrocnemius (calf) muscle of a healthy volunteer using DCS. During exercise, dynamometer recordings including footplate position, footplate angular velocity, and plantar flexion torque were obtained. Muscle fiber motions introduced artifacts into the DCS signals, causing an overestimation of blood flow changes. We show how proper co-registration of dynamometer recordings and DCS measurements enables separation of the true blood flow responses during exercise from those affected by the motion artifacts.
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Affiliation(s)
- Yu Shang
- Center for Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA
| | - T. B. Symons
- Graduate Center for Gerontology, University of Kentucky, Lexington, KY 40536, USA
| | - Turgut Durduran
- ICFO- Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - A. G. Yodh
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Guoqiang Yu
- Center for Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA
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25
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Durduran T, Choe R, Baker WB, Yodh AG. Diffuse Optics for Tissue Monitoring and Tomography. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2010; 73:076701. [PMID: 26120204 PMCID: PMC4482362 DOI: 10.1088/0034-4885/73/7/076701] [Citation(s) in RCA: 555] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This review describes the diffusion model for light transport in tissues and the medical applications of diffuse light. Diffuse optics is particularly useful for measurement of tissue hemodynamics, wherein quantitative assessment of oxy- and deoxy-hemoglobin concentrations and blood flow are desired. The theoretical basis for near-infrared or diffuse optical spectroscopy (NIRS or DOS, respectively) is developed, and the basic elements of diffuse optical tomography (DOT) are outlined. We also discuss diffuse correlation spectroscopy (DCS), a technique whereby temporal correlation functions of diffusing light are transported through tissue and are used to measure blood flow. Essential instrumentation is described, and representative brain and breast functional imaging and monitoring results illustrate the workings of these new tissue diagnostics.
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Affiliation(s)
- T Durduran
- ICFO- Institut de Ciències Fotòniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain
| | - R Choe
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - W B Baker
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - A G Yodh
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
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26
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Geraskin D, Boeth H, Kohl-Bareis M. Optical measurement of adipose tissue thickness and comparison with ultrasound, magnetic resonance imging, and callipers. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:044017. [PMID: 19725728 DOI: 10.1117/1.3184425] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Near-infrared spectroscopy is used to quantify the subcutaneous adipose tissue thickness (ATT) over five muscle groups (vastus medialis, vastus lateralis, gastrocnemius, ventral forearm and biceps brachii muscle) of healthy volunteers (n=20). The optical lipid signal (OLS) was obtained from the second derivative of broad band attenuation spectra and the lipid absorption peak (lambda=930 nm). Ultrasound and MR imaging as well as mechanical calliper readings were taken as reference methods. The data show that the OLS is a good predictor for ATT (<16 mm) with absolute and relative errors of <0.8 mm and <24%, respectively. The optical method compares favourably with calliper reading. The finding of a non-linear relationship of optical signal vs. ultrasound is explained by a theoretical two-layer model based on the diffusion approximation for the transport of photons. The crosstalk between the OLS and tissue hemoglobin concentration changes during an incremental cycling exercise was found to be small, indicating the robustness of OLS. Furthermore, the effect of ATT on spatially-resolved spectroscopy measurements is shown to decrease the calculated muscle hemoglobin concentration and to increase oxygen saturation.
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Affiliation(s)
- Dmitri Geraskin
- University of Applied Sciences Koblenz, RheinAhrCampus, Suedallee 2, Remagen, 53424, Germany
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27
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Matvienko A, Mandelis A, Abrams S. Robust multiparameter method of evaluating the optical and thermal properties of a layered tissue structure using photothermal radiometry. APPLIED OPTICS 2009; 48:3192-3203. [PMID: 19516364 DOI: 10.1364/ao.48.003192] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The thermal and optical properties of multilayered dental tissue structure, the result of the surface-grown prismless layer on enamel, were evaluated simultaneously using multiparameter fits of photothermal radiometry frequency responses. The photothermal field generated in a tooth sample with near-infrared laser excitation was described using a coupled diffuse-photon-density and thermal wave model. The optical (absorption and scattering) coefficients and thermal parameters (spectrally averaged infrared emissivity, thermal diffusivity and conductivity) of each layer, as well as the thickness of the upper prismless enamel layer, were fitted using a multiparameter simplex downhill minimization algorithm. The results show that the proposed fitting approach can increase robustness of the multiparameter estimation of tissue properties in the case of ill-defined multiparameter fits, which are unavoidable in in vivo tissue evaluation. The described method can readily be used for noninvasive in vitro or in vivo characterization of a wide range of layered biological tissues.
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Affiliation(s)
- Anna Matvienko
- Center for Advanced Diffusion-Wave Technologies, Department of Mechanical and Industrial Engineering,University of Toronto, 5 King's College Road, Toronto, ON, M5S 3G8, Canada.
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Sayli O, Aksel EB, Akin A. Crosstalk and error analysis of fat layer on continuous wave near-infrared spectroscopy measurements. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:064019. [PMID: 19123665 DOI: 10.1117/1.3028008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Accurate estimation of concentration changes in muscles by continuous wave near-IR spectroscopy for muscle measurements suffers from underestimation and crosstalk problems due to the presence of superficial skin and fat layers. Underestimation error is basically caused by a homogeneous medium assumption in the calculations leading to the partial volume effect. The homogeneous medium assumption and wavelength dependence of mean partial path length in the muscle layer cause the crosstalk. We investigate underestimation errors and crosstalk by Monte Carlo simulations with a three layered (skin-fat-muscle) tissue model for a two-wavelength system where the choice of first wavelength is in the 675- to 775-nm range and the second wavelength is in the 825- to 900-nm range. Means of absolute underestimation errors and crosstalk over the considered wavelength pairs are found to be higher for greater fat thicknesses. Estimation errors of concentration changes for Hb and HbO(2) are calculated to be close for an ischemia type protocol where both Hb and HbO(2) are assumed to have equal magnitude but opposite concentration changes. The minimum estimation errors are found for the 700825- and 725825-nm pairs for this protocol.
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Affiliation(s)
- Omer Sayli
- Bogazici University, Institute of Biomedical Engineering, Bebek, Istanbul, 34342, Turkey
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29
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Xu C, Das M, Ardeshirpour Y, Zhu Q. Image reconstruction method for a two-layer tissue structure accounts for chest-wall effects in breast imaging. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:064029. [PMID: 19123675 PMCID: PMC2647560 DOI: 10.1117/1.3041497] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
We develop a new tomographic imaging reconstruction algorithm for a two-layer tissue structure. Simulations and phantom experiments show more accurate reconstruction of target optical properties compared with those results obtained from a semi-infinite tissue model for layered structures. This improvement is mainly attributed to the more accurate estimation of background optical properties and more accurate estimation of weight matrix for imaging reconstruction by considering the light propagation effect in the second layer. Clinical results of breast lesions are also presented to demonstrate the utility of this new imaging algorithm.
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Affiliation(s)
- Chen Xu
- University of Connecticut, Department of Electrical and Computer Engineering, Storrs, Connecticut 06269, USA
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30
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Nielsen K, Zhao L, Ryzhikov G, Biryulina M, Sommersten E, Stamnes J, Stamnes K, Moan J. Retrieval of the physiological state of human skin from UV–Vis reflectance spectra – A feasibility study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2008; 93:23-31. [DOI: 10.1016/j.jphotobiol.2008.06.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2007] [Revised: 05/08/2008] [Accepted: 06/17/2008] [Indexed: 11/28/2022]
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31
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Comsa DC, Farrell TJ, Patterson MS. Quantitative fluorescence imaging of point-like sources in small animals. Phys Med Biol 2008; 53:5797-814. [PMID: 18827315 DOI: 10.1088/0031-9155/53/20/016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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32
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Tseng SH, Hayakawa CK, Spanier J, Durkin AJ. Determination of optical properties of superficial volumes of layered tissue phantoms. IEEE Trans Biomed Eng 2008; 55:335-9. [PMID: 18232377 DOI: 10.1109/tbme.2007.910685] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Previously, we reported the design of a new diffusing probe that employs a standard two-layer diffusion model to recover the optical properties of turbid samples. This particular probe had a source-detector separation of 2.5 mm and performance was validated with Monte Carlo simulations and homogeneous phantom experiments. The goal of the current study is to characterize the performance of this new method in the context of two-layer phantoms that mimic the optical properties of human skin. We analyze the accuracy of the recovered top layer optical properties and their dependences on the thickness of the top layer of two-layer phantoms. Our results demonstrate that the optical properties of the top layer can be accurately determined with a 1.6 mm source-detector separation diffusing probe when this layer thickness is as thin as 1 mm. Monte Carlo simulations illustrate that the interrogation depth can be further decreased by shortening the source-detector separation.
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Affiliation(s)
- Sheng-Hao Tseng
- Johnson and Johnson Consumer and Personal Products Worldwide, Skillman, NJ 08558, USA.
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33
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Tseng SH, Grant A, Durkin AJ. In vivo determination of skin near-infrared optical properties using diffuse optical spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:014016. [PMID: 18315374 PMCID: PMC2626348 DOI: 10.1117/1.2829772] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We develop a superficial diffusing probe with a 3 mm source-detector separation that can be used in combination with diffuse optical spectroscopic (DOS) methods to noninvasively determine full-spectrum optical properties of superficial in vivo skin in the wavelength range from 650 to 1000 nm. This new probe uses a highly scattering layer to diffuse photons emitted from a collimated light source and relies on a two-layer diffusion model to determine tissue absorption coefficient mu a and reduced scattering coefficient mu's. By employing the probe to measure two-layer phantoms that mimic the optical properties of skin, we demonstrate that the probe has an interrogation depth of 1 to 2 mm. We carry out SSFDPM (steady state frequency-domain photon migration) measurements using this new probe on the volar forearm and palm of 15 subjects, including five subjects of African descent, five Asians, and five Caucasians. The optical properties of in vivo skin determined using the superficial diffusing probe show considerable similarity to published optical properties of carefully prepared ex vivo epidermis+dermis.
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Affiliation(s)
- Sheng-Hao Tseng
- University of California, Irvine, Beckman Laser Institute, Laser Microbeam and Medical Program, Irvine, California 92617, USA.
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34
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Comsa DC, Farrell TJ, Patterson MS. Bioluminescence imaging of point sources implanted in small animals post mortem: evaluation of a method for estimating source strength and depth. Phys Med Biol 2007; 52:5415-28. [PMID: 17762095 DOI: 10.1088/0031-9155/52/17/021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The performance of a simple approach for the in vivo reconstruction of bioluminescent point sources in small animals was evaluated. The method uses the diffusion approximation as a forward model of light propagation from a point source in a homogeneous tissue to find the source depth and power. The optical properties of the tissue are estimated from reflectance images obtained at the same location on the animal. It was possible to localize point sources implanted in mice, 2-8 mm deep, to within 1 mm. The same performance was achieved for sources implanted in rat abdomens when the effects of tissue surface curvature were eliminated. The source power was reconstructed within a factor of 2 of the true power for the given range of depths, even though the apparent brightness of the source varied by several orders of magnitude. The study also showed that reconstructions using optical properties measured in situ were superior to those based on data in the literature.
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Affiliation(s)
- D C Comsa
- Juravinski Cancer Centre and McMaster University, 699 Concession Street, Hamilton, ON L8V 5C2, Canada.
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35
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Sato C, Yamaguchi T, Seida M, Ota Y, Yu I, Iguchi Y, Nemoto M, Hoshi Y. Intraoperative monitoring of depth-dependent hemoglobin concentration changes during carotid endarterectomy by time-resolved spectroscopy. APPLIED OPTICS 2007; 46:2785-92. [PMID: 17446928 DOI: 10.1364/ao.46.002785] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
By measuring the adult human head during carotid endarterectomy, we investigate the depth sensitivity of two methods for deriving the absorption coefficient changes (Dmu(a)) from time-resolved reflectance data to absorption changes in inhomogeneous media: (1) the curve-fitting method based on the diffusion equation (DE-fit method) and (2) the time-independent calculation based on the modified Lambert-Beer law (MLB method). Remarkable differences in the determined values of Dmu(a) caused by clamping the external carotid artery and subsequently clamping the common carotid artery were observed between the methods. The DE-fit method was more sensitive to mu(a) changes in cerebral tissues, whereas the MLB method was rather sensitive to mu(a) changes in the extracerebral tissues. Our results indicated that the DE-fit was useful for monitoring the cerebral blood circulation and oxygenation during neurosurgical operations. In addition, the combined evaluation of mu(a) changes with the DE-fit and MLB methods will provide us with more available information about the hemodynamic changes in the depth direction.
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Affiliation(s)
- Chie Sato
- Integrated Neuroscience Research Team, Tokyo Institute of Psychiatry, Tokyo, Japan.
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36
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Bisland SK, Austin JW, Hubert DP, Lilge L. Photodynamic Actinometry Using Microspheres: Concept, Development and Responsivity ¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2004.tb00023.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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37
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Seo I, You JS, Hayakawa CK, Venugopalan V. Perturbation and differential Monte Carlo methods for measurement of optical properties in a layered epithelial tissue model. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:014030. [PMID: 17343505 DOI: 10.1117/1.2697735] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The use of perturbation and differential Monte Carlo (pMC/dMC) methods in conjunction with nonlinear optimization algorithms were proposed recently as a means to solve inverse photon migration problems in regionwise heterogeneous turbid media. We demonstrate the application of pMC/dMC methods for the recovery of optical properties in a two-layer extended epithelial tissue model from experimental measurements of spatially resolved diffuse reflectance. The results demonstrate that pMC/dMC methods provide a rapid and accurate approach to solve two-region inverse photon migration problems in the transport regime, that is, on spatial scales smaller than a transport mean free path and in media where optical scattering need not dominate absorption. The pMC/dMC approach is found to be effective over a broad range of absorption (50 to 400%) and scattering (70 to 130%) perturbations. The recovery of optical properties from spatially resolved diffuse reflectance measurements is examined for different sets of source-detector separation. These results provide some guidance for the design of compact fiber-based probes to determine and isolate optical properties from both epithelial and stromal layers of superficial tissues.
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Affiliation(s)
- InSeok Seo
- University of California, Irvine, Department of Chemical Engineering and Materials Science, Irvine, California 92697, USA
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38
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Das M, Xu C, Zhu Q. Analytical solution for light propagation in a two-layer tissue structure with a tilted interface for breast imaging. APPLIED OPTICS 2006; 45:5027-36. [PMID: 16807614 PMCID: PMC3776600 DOI: 10.1364/ao.45.005027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Reflectance measurement of breast tissue is influenced by the underlying chest wall, which is often tilted as seen by the detection probe. We develop an analytical solution of light propagation in a two-layer tissue structure with tilted interface and refractive index difference between the layers. We validate the analytical solution with Monte Carlo simulations and phantom experiments, and a good agreement is seen. The influence of varying the tilting angle of the interface on the reflectance is discussed for two types of layered structures. Further, we apply the developed analytical solution to obtain the optical properties of breast tissue and chest wall from clinical data. Inverse calculation using the developed solution applied to the data obtained from Monte Carlo simulations shows that the optical properties of both layers are obtained with higher accuracy as compared to using a simple two-layer model ignoring the interface tilt. This is expected to improve the accuracy in estimating the optical properties of breast tissue, thus enhancing the accuracy of optical tomography of breast tumors.
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39
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Liu Q, Ramanujam N. Sequential estimation of optical properties of a two-layered epithelial tissue model from depth-resolved ultraviolet-visible diffuse reflectance spectra. APPLIED OPTICS 2006; 45:4776-90. [PMID: 16799693 DOI: 10.1364/ao.45.004776] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A method for estimating the optical properties of two-layered media (such as squamous epithelial tissue) over a range of wavelengths in the ultraviolet-visible spectrum is proposed and tested with Monte Carlo modeling. The method first used a fiber-optic probe with angled illumination and the collection fibers placed at a small separation (<or=300 microm) to restrict the transport of detected light to the top layer. A Monte Carlo-based inverse model for a homogeneous medium was employed to estimate the top layer optical properties from the measured diffuse reflectance spectrum. Then a flat-tip probe with a large source-detector separation (>or=1000 microm) was used to detect diffuse reflectance preferentially from the bottom layer. A second Monte Carlo-based inverse model for a two-layered medium was applied to estimate the bottom layer optical properties, as well as the top layer thickness, given that the top layer optical properties have been estimated. The results of Monte Carlo validation show that this method works well for an epithelial tissue model with a top layer thickness ranging from 200 to 500 microm. For most thicknesses within this range, the absorption coefficients were estimated to within 15% of the true values, the reduced scattering coefficients were estimated to within 20% and the top layer thicknesses were estimated to within 20%. The application of a variance reduction technique to the Monte Carlo modeling proved to be effective in improving the accuracy with which the optical properties are estimated.
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Affiliation(s)
- Quan Liu
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708-0281, USA.
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40
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Donner C, Jensen HW. Rapid simulation of steady-state spatially resolved reflectance and transmittance profiles of multilayered turbid materials. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2006; 23:1382-90. [PMID: 16715157 DOI: 10.1364/josaa.23.001382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We present a technique for efficiently computing the reflection and transmission of light by arbitrary systems of turbid layers. To approximate the steady-state reflectance and transmittance without the need to solve difficult boundary conditions, we convolve the reflectance and transmittance profiles of individual layers. We extend single-slab boundary conditions to handle index-of-refraction mismatches between turbid slabs and account for interlayer scattering by applying methods similar to Kubelka-Munk theory in frequency space. We demonstrate good agreement between the reflectance and the transmittance predicted by our model and numerical Monte Carlo methods and show that the far-source reflectance and transmittance of multilayered turbid materials are dominated by interlayer scattering.
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Affiliation(s)
- Craig Donner
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla 92093-0404, USA.
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41
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Shimada M, Hoshi Y, Yamada Y. Simple algorithm for the measurement of absorption coefficients of a two-layered medium by spatially resolved and time-resolved reflectance. APPLIED OPTICS 2005; 44:7554-63. [PMID: 16363780 DOI: 10.1364/ao.44.007554] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
An inversion procedure for the recovery of absorption coefficients of a two-layered semi-infinite diffusive medium by use of time-resolved reflectance measured at two different source-detector distances is proposed. The inversion procedure is based on the property of the photon diffusion equation; i.e., the solution of the diffusion equation for the time-resolved reflectance measured at a longer source--detector distance coincides with that measured at a shorter one by a proper temporal, spatial, and intensity transformation. This inversion procedure, used together with the results of one set of Monte Carlo simulations, is validated as working well when the values of the scattering coefficients of the two layers and the thickness of the first layer are within a range of interest in tissue optics.
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Affiliation(s)
- Miho Shimada
- High Energy Accelerator Research Organization, KEK, Tsukuba, Ibaraki, Japan.
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42
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Sato C, Shimada M, Yamada Y, Hoshi Y. Extraction of depth-dependent signals from time-resolved reflectance in layered turbid media. JOURNAL OF BIOMEDICAL OPTICS 2005; 10:064008. [PMID: 16409073 DOI: 10.1117/1.2136312] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We try a new approach with near-IR time-resolved spectroscopy, to separate optical signals originated in the upper layer from those in the lower layer and to selectively determine the absorption coefficient (mu(a)) of each layer in a two-layered turbid medium. The difference curve in the temporal profiles of light attenuation between a target and a reference medium is divided into segments along the time axis, and a slope of each segment is calculated to determine the depth-dependent mu(a). The depth-dependent mu(a) values are estimated under various conditions in which mu(a) and the reduced scattering coefficient (mu(s)') of each layer are changed with a Monte Carlo simulation and in phantom experiments. Temporal variation of them represents the difference in mu(a) between two layers when mu(s)' of a reference is the same as that of the upper layer of the target. The discrepancies between calculated mu(a) and the real mu(a) depend on the ratio of the real mu(a) of the upper layer to that of the lower layer, and our approach enables us to estimate the ratio of mu(a) between the two layers. These results suggest the potential that mu(a) of the lower layer can be determined by our procedure.
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Affiliation(s)
- Chie Sato
- Tokyo Institute of Psychiatry, Department of Integrated Neuroscience, 2-1-8 Kamikitazawa, Setagaya-ku, Tokyo 156-8585, Japan.
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43
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Georgakoudi I, Van Dam J. Characterization of Dysplastic Tissue Morphology and Biochemistry in Barrett’s Esophagus using Diffuse Reflectance and Light Scattering Spectroscopy. TECHNIQUES IN GASTROINTESTINAL ENDOSCOPY 2005. [DOI: 10.1016/j.tgie.2005.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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44
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Yu G, Durduran T, Lech G, Zhou C, Chance B, Mohler ER, Yodh AG. Time-dependent blood flow and oxygenation in human skeletal muscles measured with noninvasive near-infrared diffuse optical spectroscopies. JOURNAL OF BIOMEDICAL OPTICS 2005; 10:024027. [PMID: 15910100 DOI: 10.1117/1.1884603] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We have employed near-infrared optical methods to measure noninvasively the dynamics of muscle blood flow and oxygen saturation (StO2) during cuff occlusion and plantar flexion exercise. Relative muscle oxygen consumption (rVO2) was also computed from these data. Diffuse correlation spectroscopy provides information about blood flow, and diffuse reflectance spectroscopy provides information about blood oxygenation. Ten healthy subjects and one patient with peripheral arterial disease (PAD) were studied during 3-min arterial cuff occlusion of arm and leg, and during 1-min plantar flexion exercise. Signals from different layers (cutaneous tissues and muscles) during cuff occlusion were differentiated, revealing strong hemodynamic responses from muscle layers. During exercise in healthy legs, the observed approximately 4.7 fold increase in relative blood flow (rBF) was significantly lower than the corresponding increase in rVO2 (approximately 7 fold). The magnitudes of rBF and rVO2 during exercise in the PAD patient were approximately 1/2 of the healthy controls, and the StO2 recovery time was twice that of the controls. The hybrid instrument improves upon current technologies for measuring muscle responses by simultaneously measuring rBF and StO2. The instrument thus provides a method for evaluation of microcirculation and muscle metabolism in patients with vascular diseases.
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Affiliation(s)
- Guoqiang Yu
- University of Pennsylvania, Department of Physics and Astronomy, Philadelphia, Pennsylvania 19104, USA.
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45
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Hattery D, Hattery B, Chernomordik V, Smith P, Loew M, Mulshine J, Gandjbakhche A. Differential oblique angle spectroscopy of the oral epithelium. JOURNAL OF BIOMEDICAL OPTICS 2004; 9:951-60. [PMID: 15447016 DOI: 10.1117/1.1781161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Increasing evidence suggests that inflammation may contribute to the process of carcinogenesis. This is the basis of several clinical trials evaluating potential chemopreventive drugs. These trials require quantitative assessments of inflammation, which, for the oral epithelium, are traditionally provided by histopathological evaluation. To reduce patient discomfort and morbidity of tissue biopsy procedures, we develop a noninvasive alternative using diffuse reflectance spectroscopy to measure epithelial thickness as an index of tissue inflammation. Although any optical system has the potential for probing near-surface structures, traditional methods of accounting for scattering of photons are generally invalid for typical epithelial thicknesses. We develop a single-scattering theory that is valid for typical epithelial thicknesses. The theory accurately predicts a distinctive feature that can be used to quantify epithelial thickness given intensity measurements with sources at two different angles relative to the tissue surface. This differential measure approach has acute sensitivity to small, layer-related changes in scattering coefficients. To assess the capability of our method to quantify epithelial thickness, detailed Monte Carlo simulations and measurements on phantom models of a two-layered structure are performed. The results show that the intensity ratio maximum feature can be used to quantify epithelial thickness with an error less than 30% despite fourfold changes in scattering coefficients and 10-fold changes in absorption coefficients. An initial study using a simple two-source, four-detector probe on patients shows that the technique has promise. We believe that this new method will perform well on patients with diverse tissue optical characteristics and therefore be of practical clinical value for quantifying epithelial thickness in vivo.
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Affiliation(s)
- David Hattery
- National Institutes of Health, National Institute of Child Health and Human Development, Laboratory of Integrative and Medical Biophysics, Building 9, Room B1E11, Bethesda, Maryland 20892-0924, USA.
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46
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Stasic D, Farrell TJ, Patterson MS. The use of spatially resolved fluorescence and reflectance to determine interface depth in layered fluorophore distributions. Phys Med Biol 2004; 48:3459-74. [PMID: 14653556 DOI: 10.1088/0031-9155/48/21/001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The possibility of using spatially resolved fluorescence and reflectance measurements to recover tissue optical properties, fluorophore concentration and the thickness of a superficial layer in a two-layer geometry was investigated. A diffusion theory model was used to fit reflectance and fluorescence data generated using Monte Carlo simulations or experimentally obtained using tissue-simulating phantoms. Initial analysis fitting diffusion theory generated data suggested that it should be possible to recover all parameters from a single set of spatially resolved fluorescence and reflectance measurements. However, when Monte Carlo or experimental data were fitted the results were less impressive. Overall, it was shown that there is a strong coupling between interface depth, fluorophore concentration and tissue absorption, especially at larger depths. The recovery of all input parameters from a single set of spatially resolved measurements was limited to interface depths less than 3 mm, which is a reasonable range for measuring fluorophore in skin. When the tissue optical properties and fluorophore concentrations were known, then the interface depth could be monitored with good accuracy in simulated serial measurements. These results may also point to deficiencies in the diffusion theory model that introduce significant errors in the fitted results.
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Affiliation(s)
- Dragana Stasic
- Hamilton Regional Cancer Centre, McMaster University, 699 Concession Street, Hamilton, Ontario, L8V 5C2, Canada
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47
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Garofalakis A, Zacharakis G, Filippidis G, Sanidas E, Tsiftsis DD, Ntziachristos V, Papazoglou TG, Ripoll J. Characterization of the reduced scattering coefficient for optically thin samples: theory and experiments. ACTA ACUST UNITED AC 2004. [DOI: 10.1088/1464-4258/6/7/012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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48
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Polonsky IN, Davis AB. Lateral photon transport in dense scattering and weakly absorbing media of finite thickness: asymptotic analysis of the space-time Green function. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2004; 21:1018-1025. [PMID: 15191184 DOI: 10.1364/josaa.21.001018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The asymptotic law for the radial distribution of radiance density from an isotropic point source placed in a slab of homogeneous absorbing and scattering material is obtained within the framework of diffusion theory. The exponential shape of the tail of the resulting Green function has been observed but was not theoretically explained until now. We derive formulas for both the steady-state and the time-dependent problems. The theoretical results are verified by comparison with Monte Carlo simulations.
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Affiliation(s)
- Igor N Polonsky
- Los Alamos National Laboratory, Space and Remote Sensing Sciences Group (ISR-2), Los Alamos, New Mexico 87545-0000, USA.
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49
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Liebert A, Wabnitz H, Steinbrink J, Obrig H, Möller M, Macdonald R, Villringer A, Rinneberg H. Time-resolved multidistance near-infrared spectroscopy of the adult head: intracerebral and extracerebral absorption changes from moments of distribution of times of flight of photons. APPLIED OPTICS 2004; 43:3037-47. [PMID: 15176190 DOI: 10.1364/ao.43.003037] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We report on multidistance time-resolved diffuse reflectance spectroscopy of the head of a healthy adult after intravenous administration of a bolus of indocyanine green. Intracerebral and extracerebral changes in absorption are deduced from moments (integral, mean time of flight, and variance) of the distributions of times of flight of photons (DTOFs), recorded simultaneously at four different source-detector separations. We calculate the sensitivity factors converting depth-dependent changes in absorption into changes of moments of DTOFs by Monte Carlo simulations by using a layered model of the head. We validate our method by analyzing moments of DTOFs simulated for the assumed changes in absorption in different layers of the head model.
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Affiliation(s)
- Adam Liebert
- Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin, Germany
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Torricelli A, Quaresima V, Pifferi A, Biscotti G, Spinelli L, Taroni P, Ferrari M, Cubeddu R. Mapping of calf muscle oxygenation and haemoglobin content during dynamic plantar flexion exercise by multi-channel time-resolved near-infrared spectroscopy. Phys Med Biol 2004; 49:685-99. [PMID: 15070196 DOI: 10.1088/0031-9155/49/5/003] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A compact and fast multi-channel time-resolved near-infrared spectroscopy system for tissue oximetry was developed. It employs semiconductor laser and fibre optics for delivery of optical signals. Photons are collected by eight 1 mm fibres and detected by a multianode photomultiplier. A time-correlated single photon counting board is used for the parallel acquisition of time-resolved reflectance curves. Estimate of the reduced scattering coefficient is achieved by fitting with a standard model of diffusion theory, while the modified Lambert-Beer law is used to assess the absorption coefficient. In vivo measurements were performed on five healthy volunteers to monitor spatial changes in calf muscle (medial and lateral gastrocnemius; MG, LG) oxygen saturation (SmO2) and total haemoglobin concentration (tHb) during dynamic plantar flexion exercise performed at 50% of the maximal voluntary contraction. At rest SmO2 was 73.0 +/- 0.9 and 70.5 +/- 1.7% in MG and LG, respectively (P = 0.045). At the end of the exercise, SmO2 decreased (69.1 +/- 1.8 and 63.8 +/- 2.1% in MG and LG, respectively; P < 0.01). The LG desaturation was greater than the MG desaturation (P < 0.02). These results strengthen the role of time-resolved near-infrared spectroscopy as a powerful tool for investigating the spatial and temporal features of muscle SmO2 and tHb.
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Affiliation(s)
- Alessandro Torricelli
- INFM-Dipartimento di Fisica and IFN-CNR, Politecnico di Milano, Piazza Leonardo da Vinci 32, 1-20133 Milan, Italy
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